The present disclosure is related to air filtering systems for low temperature catalytic processes. In particular, the disclosure is directed to air filters for use with a fuel cell apparatus.
It is accepted that in today""s world all atmospheric air has some degree of contaminants present in it. These contaminants may be large items, for example, blown leaves, loose papers and other debris, cottonwood tree blossoms, and insects; or the contaminants may be small enough, such as particulates, that they are suspended in the atmosphere. Examples of such particulates include dust, tree pollen, smog, and smoke particulates.
Chemical contaminants are also widely present in atmospheric air. Although many are the result of man-made pollution, other chemicals occur naturally. Typical contaminants include volatile organic compounds such as methane, butane, propane, and other hydrocarbons, also ammonia, oxides of nitrogen, oxides of sulfur, carbon monoxide, hydrogen sulfide, etc.
Most of today""s machines, such as automobiles, are designed to be able to either filter out or withstand any contaminants that could cause problems to their operation. For example, large contaminants such as leaves and paper are removed from the intake air stream by the automobiles"" grills and various vents. These features also remove small animals such as birds, squirrels and mice that may find their way into the engine area. Finer contaminants such as dust are removed by an air filter present in the engine compartment. For the typical automobile and internal combustion machines (such as lawn mowers, snowblowers, snowmobiles, etc.) chemical contaminants pose very little, if any, problems to the functioning of the machine, because the machine and the process by which it produces power, are capable of withstanding the presence of contaminants in the intake air.
There are some machines and systems that have not yet been optimized for operating in today""s contaminated atmosphere. This may be because the importance of clean intake air has not been recognized as a requirement for efficient and/or optimal operation, or because those contaminants in the air that may degrade the performance of the machine have not yet been adequately recognized or defined.
The fuel cell, a rapidly emerging source of power for both residential and commercial purposes, is one type of system that is not yet fully understood. A fuel cell is a device consisting of two electrodes (an anode and a cathode), between which is sandwiched an electrolyte. Depending on the size, shape and design of the cell, the fuel cell is capable of providing enough energy to run a cell phone, a computer, an automobile, a residential house, or even a power plant. Fuel cells typically operate with a fuel source being supplied to the anodic side of the cell and an oxidant being supplied to the cathodic side. An example of a commonly used fuel is hydrogen.
Many fuel cells are not designed to operate efficiently in the presence of large amounts of contaminants which may be present in the intake air that is necessary for the functioning of the fuel cell. They also have not generally been designed to handle or filter such contaminants from the intake air. This is because fuel cells, and their operation, are typically new, and their operation parameters are typically not well defined. The overall capabilities and limits of fuel cells generally are not completely understood.
What is desired, therefore, is a fuel cell that functions within environments having a wide range of contaminants.
The present invention provides an air filter assembly for filtering the intake air used in low temperature catalytic reactions, such as fuel cells. The assembly provides either particulate filtration, chemical filtration, or both, to the incoming air stream to provide a purified oxidant to the cathodic side of a catalytic reactor, such as a fuel cell.
The filter assembly captures and retains particulate and/or chemical contaminants that can harm the catalytic process. In one embodiment of the invention, a filter assembly is provided that can capture and temporarily retain the chemical contaminants, releasing the contaminants when the incoming dirty air has levels of those contaminants below the accepted level.
The filter assembly is useful in low temperature catalytic processes. In one embodiment, the filter assembly can be used on proton exchange membrane (PEM) fuel cells.
In particular in one embodiment, the invention is directed to a system for producing power. The system comprises an air filter assembly which comprises: a housing and a filter element in the housing. The housing has an inlet and an outlet, the inlet providing dirty atmospheric air to the filter assembly, and the outlet providing clean air from the filter assembly. The filter element comprises a physical or particulate filter portion constructed and arranged to remove particulate contaminants from the dirty air and a chemical filter portion constructed and arranged to remove chemical contaminants from the dirty air. The system further includes a fuel cell having an air intake port. The air filter assembly is constructed and arranged to provide clean air from the outlet of the filter assembly to the intake port of the fuel cell.
In another particular embodiment of the invention, a filter assembly for use with a fuel cell is provided. The filter assembly has a housing and a filter element in the housing. The housing has an inlet and an outlet, the inlet providing dirty air to the filter assembly, and the outlet providing clean air from the filter assembly. The filter element has a physical filter portion constructed and arranged to remove particulate contaminants from the dirty air and a chemical filter portion constructed and arranged to remove chemical contaminants from the dirty air. In particular, the chemical filter portion has a first portion constructed and arranged to remove ammonia and amines from the dirty air, the first portion comprising impregnated activated carbon adsorption media; a second portion constructed and arranged to remove acidic gases and organic materials from the dirty air, the second portion comprising impregnated activated carbon adsorption media; and a third portion constructed and arranged to oxidize contaminants in the dirty air, the third portion comprising catalyst material. A fourth portion, and any additional portions, can be included.